1. Field of the Invention
The present invention relates to a molten metal infiltrating method for manufacturing a metal based composite material such as a fiber reinforced metal.
2. Related Art
Since a metal material reinforced by a linear material such as a fiber reinforced metal is more excellent in a thermal resistance and a specific strength than an ordinary composite material, and furthermore, is excellent in electrical conduction, it has been particularly applied and developed mainly in the aerospace field, building structures or the telecommunication field.
Although such a metal reinforced by a linear material is obtained by heating to a melting temperature for the metal or more while pressurizing a linear material plated with the metal, it is usually manufactured by a method of immersing a linear material in a molten metal which has excellent productivity and is advantageous to a cost.
The method of infiltrating a linear material with a molten metal will be described below with reference to the drawings.
FIG. 4 is a model view showing an example of a pressure melting and infiltrating type linear composite material manufacturing apparatus 101.
An electric furnace 102 having a molten metal 103 in a pressure chamber 104 which can be pressurized is provided and a linear material bundle 105 (in this example, a fiber) is continuously introduced into the chamber through an inlet seal portion provided in the lower part of the chamber.
The linear material thus introduced is immersed in the molten metal in the electric furnace. At this time, the linear material bundle is infiltrated with the metal. Then, the linear material infiltrated with the metal is continuously taken out of an outlet seal portion provided in the top part of the chamber and is changed into a linear composite material 106 when the metal is solidified. The inside of the pressure chamber is pressurized by an inert gas against the molten metal. Therefore, it is possible to prevent an infiltration defect portion such as a void from being generated during the infiltration.
In the case in which such a pressure melting and infiltrating type linear composite material manufacturing apparatus is used, a comparatively excellent composite material can be obtained if the molten metal is aluminum or an aluminum alloy and the linear material is a silicon carbide (SiC) fiber or an alumina fiber. However, the silicon carbide fiber and the alumina fiber are very expensive. On the other hand, if a carbon fiber which is advantageous to a cost is used for the linear material, a gap is generated between the linear material and a matrix metal or a void (matrix infiltration defect portion) is generated because a wettability to the molten metal on the surface of the linear material is poor. Therefore, performance (electrical or mechanical performance) to be originally obtained cannot be acquired and an improvement thereof has been required.
In order to improve the wettability to the molten metal on the surface of the linear material, there has been proposed a method of previously providing a metal layer on the surface of a linear material.
As an example, a metal spraying method and a vacuum depositing method have been known.
FIG. 5 shows a model of an apparatus 107 to be used for the metal spraying and vacuum depositing method.
In FIG. 5, a pair of electrodes 108 are provided in a vacuum chamber 110 and a voltage is applied thereto. The vacuum chamber 110 is filled with a metal vapor and a metal layer is formed on the surface of a linear material 105 (in this example, a fiber) introduced continuously from the lower part of the chamber 110. Then, the linear material 109 having the metal layer formed on the surface is continuously taken out of an outlet seal portion. The chamber 110 is connected to a vacuum line and an internal pressure reducing state can be maintained.
For a pretreatment of the metal spraying and vacuum depositing method, however, troubles are easily made over the maintenance of a vacuum and effects thereof are not stable in many cases. Moreover, a cost is increased. For this reason, there has also been proposed a metal spraying and vacuum depositing apparatus having a linear material wound upon a bobbin and a winding bobbin provided in a vacuum chamber. In this case, there has been a drawback that the cost cannot be considerably reduced and productivity is much poorer.
The invention has an object to provide a molten metal infiltrating method capable of improving the conventional problems, that is, producing a linear material reinforced metal material having ideal performance with high productivity and stable productivity without considerably increasing the cost.
In order to solve the problems, a first aspect of the invention is directed to a molten metal infiltrating method for infiltrating a linear material with a molten metal, wherein a linear material previously coated with a flux is used.
Moreover, a second aspect of the invention is directed to the molten metal infiltrating method according to the first aspect of the invention, wherein a linear material to be a core is continuously introduced through an inlet seal portion provided in a bottom part of a bath container having a molten metal on a pressurized inside and is consecutively taken out of an outlet seal portion provided in a top part of the infiltrating reservoir, the linear material introduced into the bath container through the inlet seal portion being continuously coated with a flux by a flux coating reservoir provided in the vicinity of the inlet seal portion.
A third aspect of the invention is directed to a molten metal infiltrating apparatus comprising a bath container having an inlet seal portion in a bottom part and an outlet seal portion in a top part, and flux coating means for coating, with a flux, a linear material continuously introduced into the bath container through the inlet seal portion in the vicinity of the inlet seal portion.